The title of rarest metal is a matter of controversy but iridium is always one of the top contenders. In addition to being super rare, iridium's extraordinary noble character finds uses in chemistry where an equally extraordinary resistance to corrosion is called for. And extraordinary also happens to be a good adjective to describe the fetching price of this handsome metal.
This specimen of pure iridium metal, weighing a gram or two, was melted in a vacuum by passing a high current through it. No ordinary furnace can come close to melting iridium!